CFOP Quick-witted Princess Leia (F2L completion guessing)

[Tito_H]

Episode XX+4

The Imperial Army
was building a second
Death Star above the moon Endor.
Princess Leia participated in a mission to
destroy the shielding radio wave generator protecting
the Death Star…

Pursued by Imperial soldiers, Princess Leia and R2D2 managed to reach the back entrance of the fortress, which was emitting shielding radio waves. R2D2 quickly accessed the host computer to open the iron door.

After a while, R2D2 beeped to tell Princess Leia, "The iron door cannot be opened unless you solve a certain Rubik's Cube problem." He then projected a Rubik's Cube and instructions into the air.

The Rubik's Cube was scrambled as shown below, and the instructions read, “Complete F2L exactly with 8 moves. You cannot do it in more or less than 8 moves..."

(Yellow top, Orange front)


Princess Leia quickly came up with an algorithm that could be completed with 8 moves using the Key Hole method, and turned the projection cube.

(Princess Leia's solve)


However, the iron door didn't budge. "This back door hasn't been used in a long time, so something must be blocking it," Princess Leia said, and began banging and kicking on the door.

At that moment, R2D2 nudged her, saying, "Princess Leia, regarding the instructions I just gave you, there was a continuation after a million blank lines," and projected the rest. "Oops, I almost forgot to write that down. The 8 moves are based on QTM, not STM, so be careful!"

Princess Leia fumed, "How dare they present their conditions at this timing! It's a bit like Darth Sidious's methods," she said angrily, with a troubled expression on her face, since she couldn't think of a way to solve the problem.

Can someone help her?

 

[Fred]

I found a 7 QTM solution, but not an 8 mover: y F' R' F R U2 F. I also found a couple more 10 movers: y F2 U' R U R' U F U F and U' R' U' R D' F R' F' R D. Tough challenge from those dastardly Sith lords.

 

[Tito_H]

Thanks for your response, Fred.
This is just a guess, but do you happen to know the answer(solution)? That's because you presented me with three fantastic algorithms (especially that of 7 QTM) that I could never have thought of.

 

[Fred]

Thanks for your response, Fred.
This is just a guess, but do you happen to know the answer(solution)? That's because you presented me with three fantastic algorithms (especially that of 7 QTM) that I could never have thought of.

No, I didn't find the 8 move solution.

 

[Tito_H]

I hope you or someone can come up the solution quickly, since she will be almost caught by the troops.

 

[Fred]

Spoiler: Many Bothans died to bring us this information

I consulted the wise Jedi master Trangium's batch solver for these solutions:
R' U R F' R' U R F
y L' F' L U L' U F L
y2 L' U L F' D' L D F

 

[Tito_H]

Thanks, Fred.
You've just saved her & the Earth!
Good idea to consult with him.

I will tell tomorrow how Princess Leia got theough.

 

[Tito_H]

A Happy New Year!

Let's see how Princess Leia overcame this difficult situation.

She asked R2D2, "Can you hack into the host computer?" and R2D2 replied, "Yes, it is possible." She then instructed, "Then quickly swap the letters 'QTM' and 'STM' in the program source code and reboot the system."

After a while, R2D2 replied, "Reboot completed," and once again projected the instructions into the air. The instructions now read,

"… Oops, I almost forgot to write that down. The 8 moves are based on STM, not QTM, so be careful!"

She quickly completed the F2L using her own algorithm, and was able to open the iron door.

 

[Tito_H]

I found one of the solutions, R' U R F' R' U R F, very interesting.



I had never thought of temporarily putting the EP to be paired into a non-home empty slot in the process of F2L (except using Key Hole), so the R' U R at the beginning of this algorithm is an unexpected move.

And yet, the number of moves is almost the same as the algorithm I use in F2L, (U') R U' R' F R' F' R, so it was Eureka! for me.